Saturday, November 24, 2012

Airfone is a terrestric system. The calling passenger is connected to the recipient via a net of ground stations (RBS=radio base station) scattered over the country. They connect the caller with the dialed number via landline. If the plane moves from one RBS area to the next, a handoff takes place, similar to cell calls. So in general, the position of a plane can be determined by the RBS with a decent uncertainty, just like VHF ACARS messages. Because the net of RBS is more wide-meshed than the net of ARINC RGS, the uncertainty is even bigger. Nevertheless, the list delivers valuable position information.

For instance the last column - SCP duration, "Switch Control Processor" - indicates the time (in seconds) the call was connected to the dialed number. For United 93, only four RBS were involved, and each of them has an ID number: Columbus (59 - "Colombus" with a typo), Fort Wayne (26), Belleville near Detroit (91) and Coraopolis near Pittsburgh (65).

The list makes it possible to determine the time and RBS when the call was commenced as well as the time and RBS when it was disconnected.

Caller Seat Begin of Call End of Call # Handoffs

Time RBS Time RBS

Thomas Burnett 24ABC 9:30:32 Fort Wayne 9:31:19 Columbus *

Flight Attendant 34ABC 9:32:39 Fort Wayne 9:34:17 Fort Wayne

Flight Attendant 34ABC 9:31:14 Columbus 9:31:34 Columbus

Flight Attendant 33DEF 9:35:40 Detroit 9:41:45 Fort Wayne *

Flight Attendant 34ABC 9:35:48 Detroit 9:37:32 Detroit

Flight Attendant 33ABC 9:35:58 Detroit 9:37:42 Detroit

Mark Bingham 25DEF 9:36:10 Detroit 9:36:51 Detroit

Mark Bingham 25DEF 9:37:03 Detroit 9:40:05 Fort Wayne *

Jeremy Glick 27DEF 9:37:41 Detroit 11:44:00 Pittsburgh ********

Thomas Burnett 25ABC 9:37:53 Detroit 9:39:19 Detroit

Lauren Grandcolas 23DEF 9:39:21 Detroit 9:40:21 Detroit

Lauren Grandcolas 23DEF 9:40:42 Detroit 9:41:04 Detroit

Mark Bingham 25DEF 9:41:20 Detroit 9:41:36 Detroit

Lauren Grandcolas 23DEF 9:41:34 Columbus
9:41:52 Columbus

Mark Bingham 25DEF 9:41:53 Detroit 9:42:29 Detroit

Lauren Grandcolas 23DEF 9:42:03 Columbus 9:42:19 Columbus

Joseph de Luca 26DEF 9:42:13 Columbus 9:42:47 Columbus

Lauren Grandcolas 23DEF 9:42:25 Columbus 9:42:41 Columbus

Todd Beamer 32DEF 9:42:44 Detroit 9:42:48 Detroit

Todd Beamer 32DEF 9:42:44 Detroit 9:43:29 Detroit

Lauren Grandcolas 23DEF 9:42:45 Columbus 9:43:02 Columbus

Joseph de Luca 26DEF 9:43:03 Columbus 9:45:28 Columbus

Lauren Grandcolas 23DEF 9:43:24 Columbus 9:43:31 Columbus

Lauren Grandcolas 23DEF 9:43:44 Columbus 9:44:16 Columbus

Todd Beamer 32DEF 9:43:46 Detroit 9:43:49 Detroit

Todd Beamer 32DEF 9:43:48 Detroit 10:50:20 Detroit ******

Thomas Burnett 25ABC 9:44:23 Columbus 9:45:37 Columbus

Waleska Martinez 34ABC 9:45:37 Columbus 9:47:55 Columbus

Linda Gronlund 26DEF 9:46:05 Columbus 9:47:44 Columbus

Ceecee Lyles 32ABC 9:47:57 Columbus 9:49:28 Columbus

Joseph de Luca 26DEF 9:48:48 Columbus 9:48:57 Columbus

Marion Britton 33ABC 9:49:12 Columbus 9:53:01 Pittsburgh ***

Sandra Bradshaw 33DEF 9:49:30 Columbus 9:49:45 Columbus

Sandra Bradshaw 33DEF 9:50:04 Columbus 9:58:27 Pittsburgh ***

Honor Wainio 33ABC 9:53:43 Pittsburgh 9:58:23 Pittsburgh

It is unclear whether all of these RBS were operative in 2001. According to this source f.i., the Cleveland RBS was not operative in 1991. This might explain why Cleveland doesn't appear on the airfone call list. The list will certainly shed a better light on the story of the "heroes of United 93". More research is forthcoming.